Transcript Large scale topography

Tectonic and Structural Landforms
• Both endogenic
• Create large-scale landforms
• Tectonic
– produced by deep Earth process without
erosion
• Structural
– the result of exogenous forces acting on
tectonic landforms
Structural Landforms
• Convergent tectonic forces produce fold
structures
– anticlines, synclines, monoclines, dome, basins
• Compressive or tensional forces produce faulting
– fault scarps, horsts, grabens
• Faults and folds impart relief to the landscape
(until erosion gets to them)
Structure
• the attitude of a bed or stratum of beds or
strata of sedimentary rocks, as indicated
by the dip and strike.
• the disposition of the rock formations; i.e.,
the broad dips, folds, faults, and
unconformities at depth
Strike and dip
Lithology
• Relative erodibility
– Layered rocks = wide range
• Sedimentary
• Volcanic
– Massive rocks = narrow range
• Metamorphic
• Intrusive igneous
– Erodibility is not absolute
• typically shale > limestone > sandstone ~
gneiss
Lithology
Environment During Deposition
http://www.uwgb.edu/dutchs/EarthSC202Notes/sedrocks.htm
Lithology/Climate
Landforms assoc. with sedimentary rocks
• Horizontal beds
– plateau, mesa, table, butte
• Folded beds
– anticline (arches in strata), syncline (trough in
strata), cuesta, hogback
Tablelands
• Plateau/mesa/butte/chimney
http://maunakea.com/patsadv/gallery.htm
Tablelands
Tilted Layer
Cakes
• Monoclinal folding
– beds are flexed from one
level to another
• Feature = f(dip angle)
– Cuesta (gentle)
– Hogback (steep)
– Flatiron (very steep and
supported)
• Also f(rel. erodibility)
• Drainage patterns
– Parallel
– Trellis
http://www.geog.ouc.bc.ca/physgeog/contents/10l.html
Landforms Associated with Sedimentary Rocks
Mesa
Flat-topped hill capped with hard
rock
Cuesta
Gently-tilted layer of hard rock.
The gentle upper slope, on top of
the layer is called the dip slope
Hogback
A sharp ridge of hard rock, edge
of a steeply-dipping layer
http://www.uwgb.edu/dutchs/EarthSC202Notes/sedrocks.htm
Monocline:
“A double flexure connecting
strata at one level
with the same strata at
another level”
G.K. Gilbert
Ridges
• Cuestas and hogbacks
Copyright http://www.alperry.com/coal/grand_hogback.html
© J. Michael Daniels 2002
Jm Kd
“Contact”
“Dip”
“Strike”
Scarp
Slope
Dip
Slope
Jm
Kd
Delaware MI
Resistant units are typically <100’ thick and dip N at 10-16°
15
10
16
Folded Rocks – Simple
http://www.geog.ouc.bc.ca/physgeog/contents/10l.html
• Anticline/syncline
Folded –
still simple
• Plunging
– Z-folds
Simple folds drainage
• Contorted
– Metamorphic?
• Inward/outward
– Radial
– Centripetal
• Ringlike annular
Folded Rocks - Complex
Folded Rocks - Complex
Weak
Strong
Strong
Weak
Horseshoe Hills
Horseshoe Hills.km
Blunt
synclinal
nose
STss
Blunt
synclinal
nose
Sharp
anticlinal
nose
TOPOGRAPHY